1. Field of the Invention
The present invention is directed towards a method and apparatus for providing a safe, precise, and cost-effective storage tank leak detection system; and more particularly, to a method and apparatus wherein the containment integrity of a storage tank is determined by mass measurements of the stored product.
2. Background Information
Storage tanks play a vital role in today's economy. The economy, on a global scale, depends on the proper function of these tanks as they are prevalent in several industries and virtually every geographical region in the world. In light of the vital role these storage tanks play, the integrity of the tanks is placed at a premium. That is, storage tank owners are willing to invest huge sums of money in both the maintenance and inspection of such tanks.
These tanks come in all shapes and sizes, are found both below and above ground, and are used to store a wide-range of materials. Storage tank capacities range from hundreds to millions of gallons and are used to store a staggering assortment of products; these storage tanks are commonly used to store hazardous material.
As one could imagine, there is a wide range of problems associated with maintaining storage tank integrity, particularly with above ground storage tanks. Given the enormous dimensions of above ground tanks, the corrosive products contained within the tanks, the incredible mass of the stored product, and the extreme weather conditions the tanks are subjected to; it is plain to see that above ground storage tank leaks are an all-to-common problem. Using the United States Environmental Protection Agency leak detection threshold criteria of 0.05 gallons per hour in a 10,000-gallon underground tank, that threshold would equate to a 15 gallon per hour detection level in an 80,000 barrel above ground tank. Given the limited number of systems capable of meeting the EPA's underground storage tank leak detection threshold and the added difficulties associated with above ground tanks, the difficulty in protecting against and detecting leaks is easily seen.
However, the recognized difficulty in preventing storage tank leaks does not mitigate the duties or liabilities imposed on responsible parties. Tremendous environmental and economic consequences and the threat of litigation and clean up costs associated with storage tank leaks force responsible parties to invest large sums of money in the maintenance and inspection of the tanks. Tank inspections are costly with respect to the amount of money spent, the danger presented to the inspectors and the environment, and production downtime. In fact, these inspections often remove a tank from service for more than one month. The threat of liability also forces responsible parties to spend money unnecessarily for the maintenance of these tanks. Moreover, liability does not end with litigation and clean-up costs.
Currently, responsible parties are, in some countries, being incarcerated as a direct result of storage tanks leaks. These leaks have contaminated surrounding ground water, some of which serves as drinking water for local residents. As such, the facilities associated with such incidents have been shutdown until compliance with emissions regulations can be established beyond reasonable doubt. Such proof, in turn, is dependent on proof of reliable and sufficiently accurate detection systems and methods for proving such compliance. Each day the shuttered facilities remain inoperative adds to an already tremendous amount of money lost.
Prior to the present invention (to be described in detail hereafter), there are simply no known systems or methods by which the leak detection requirements can be met. Presently available leak detection systems lack detection thresholds low enough to detect leaks down to permissible upper leakage limits for above ground storage tanks.
Clearly, for the reasons set forth above, there is a dire and immediate need for the ability to determine, with far more precision than presently possible through use of presently available systems and methods, the presence and degree of leakage from above ground storage tanks, at least to the extent of proving compliance with applicable storage tank leakage regulations or statutes.